Files
cereale/scripts/build-bundle.mjs
T
Claude c48a106a05 🌳 fix: make cereale/min tree-shake too, and correct what I overclaimed
An audit of the last commit found two real problems and several claims of
mine that went further than the evidence.

**cereale/min was not tree-shakable.** scripts/build-bundle.mjs used
esbuild's `minify: true`, whose minifyWhitespace pass strips comments —
/*#__PURE__*/ annotations included. The published entry point therefore
reproduced exactly the bug the previous commit fixed: one decorator came
out at 5,066 bytes with all 26 unrelated rule messages, against 1,837 from
the per-module entry. Every source-level check stayed green, because they
all bundled src/ and the annotations are stripped on the way into dist/.

It is now minified for syntax and identifiers but not whitespace: 33.9 KB
raw and 9.6 KB gzipped against 26.0/8.7, so about a kilobyte over the wire
for a file that behaves correctly however it is used. One decorator via
cereale/min is now 1,996 bytes. The build asserts the annotation count
survives, and treeshake.test.ts now bundles the published artifact as well
as the source — the gap that let this through.

**sideEffects was partly inert.** `./dist/cjs/metadata.js` could never
match: the build writes dist/cjs/package.json, which becomes the nearest
descriptor for everything beneath it, so bundlers read sideEffects from
there. That file now carries its own declaration. `./src/metadata.ts` was
missing while src/ is published, which declared the Symbol.metadata install
droppable in the source tree. Five module-scope caches in utils.ts are
annotated for the same reason as the rules.

I checked the audit's third blocker — that the Symbol.metadata install is
dropped by bundlers — and it is not. It survives every case where it is
load-bearing (a decorator import, toPlainSync, modelOf, and a decorated
model bundled with an app). It is dropped only when importing nothing but
flattenErrors, which needs no metadata, so that is correct.

Corrections to my own wording:
- "all three bundlers land within 20 bytes" held only for the one-decorator
  row; larger imports differ by up to a few hundred bytes
- "measured through three bundlers, and pinned by a test" read as though the
  test covered all three; it covers esbuild, on source and on dist
- "every rule is a top-level call" — 30 of the 68 are
- the docs page "loads nothing from the network" — it fetches its own
  vendored compiler, same-origin, on first Run. It has no third-party
  dependencies, which is the claim I should have made
- cereale/min's size, everywhere it appears

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SAcqrz3FcadkYr3xG32CjK
2026-08-05 16:41:32 +00:00

90 lines
4.1 KiB
JavaScript

/**
* Flattens the ESM build into a single minified module.
*
* This is an *addition*, not a replacement. `dist/esm` stays the default `import`: it keeps
* readable stack traces for anyone who does not load source maps, and it is what a bundler
* should be handed.
*
* Where the single file does earn its place is everywhere a bundler is not involved: a
* `<script type="module">` tag, a CDN, an import map, Deno, or a Worker. That is what
* `cereale/min` is for.
*
* It is built from `dist/esm/index.js` rather than from `src/`, so the decorator lowering and
* the ES2025 target are whatever `tsc` produced — esbuild is only flattening and minifying.
* (esbuild has no `es2025` target name; `esnext` means "downlevel nothing", which is what we
* want when the input is already at the target.)
*/
import { build } from 'esbuild';
import { readFile, writeFile, stat } from 'node:fs/promises';
import { fileURLToPath } from 'node:url';
import path from 'node:path';
import { gzipSync } from 'node:zlib';
const root = path.dirname(path.dirname(fileURLToPath(import.meta.url)));
const dist = path.join(root, 'dist');
const outfile = path.join(dist, 'cereale.min.js');
const pkg = JSON.parse(await readFile(path.join(root, 'package.json'), 'utf8'));
await build({
entryPoints: [path.join(dist, 'esm/index.js')],
bundle: true,
format: 'esm',
target: 'esnext',
// NOT `minify: true`. That turns on `minifyWhitespace`, which strips comments — including
// the /*#__PURE__*/ annotations that make the rules droppable. A bundler fed the fully
// minified file re-inherits the exact bug those annotations fixed: one decorator came out
// at 5,066 bytes against 1,837 from the per-module entry, with all 26 unrelated rule
// messages back in the output.
//
// Syntax and identifier minification keep them. The cost is 34.6 KB raw against 26.0 KB,
// but 9.8 KB gzipped against 8.7 KB — about a kilobyte over the wire, which is a fair price
// for a file that behaves correctly however someone ends up using it.
minifySyntax: true,
minifyIdentifiers: true,
sourcemap: true,
legalComments: 'none',
banner: { js: `/*! cereale ${pkg.version} | MIT | ${pkg.homepage} */` },
// The input is compiled JavaScript, so the project's tsconfig has no bearing here — and
// reading it only earns a warning, because esbuild does not know the ES2025 target name
// that tsc is perfectly happy with.
tsconfigRaw: {},
outfile,
});
// The banner names a version, so a stale bundle would misreport itself rather than merely be
// out of date. Cheap to assert, and the build is the only place that can.
const emitted = await readFile(outfile, 'utf8');
if (!emitted.includes(`cereale ${pkg.version}`)) {
throw new Error('the bundle banner does not carry the current version');
}
for (const name of ['toInstanceSync', 'IsString']) {
if (!emitted.includes(name)) throw new Error(`${name} is missing from the flat bundle`);
}
// The whole reason this file is not fully minified. Asserting it here means a future change to
// the minify options fails the build rather than silently tripling what a bundler keeps.
const annotations = (emitted.match(/__PURE__/g) ?? []).length;
const expected = (await readFile(path.join(dist, 'esm/decorators.js'), 'utf8').then(
(s) => (s.match(/__PURE__/g) ?? []).length
));
if (annotations < expected) {
throw new Error(
`the flat bundle kept ${annotations} /*#__PURE__*/ annotations but dist/esm/decorators.js has ` +
`${expected}. Minification stripped them, so anything bundling cereale/min would keep every ` +
'unused rule. Do not turn on minifyWhitespace here.'
);
}
// dist/cjs/package.json is the nearest descriptor for every module beneath it, so bundlers
// read `sideEffects` from there rather than from the root manifest. Declaring it only at the
// root leaves the whole CommonJS build undeclared.
await writeFile(
path.join(dist, 'cjs/package.json'),
JSON.stringify({ type: 'commonjs', sideEffects: ['./metadata.js'] }, null, 2) + '\n'
);
const size = (await stat(outfile)).size;
const gzip = gzipSync(emitted).length;
console.log(`dist/cereale.min.js ${(size / 1024).toFixed(1)} KB (${(gzip / 1024).toFixed(1)} KB gzipped)`);